This invention relates to an apparatus and method to extract material from a running length of fiber. Particularly, this invention can be used to extract a pre-spinning polymer solvent from a solution spun fiber by solvent to solvent extraction in a conduit by moving a continuous running length of the fiber through the conduit and flowing the extraction solvent through the conduit to remove the pre-spinning polymer solvent from the fiber.
A prior method to extract mineral oil from polyethylene solution spun fiber and a method to manufacture such fiber is disclosed in U.S. Pat. No. 4,413,110 hereby incorporated by reference. A process to purify both the solvent and the mineral oil for recycle and/or reuse is disclosed in pending U.S. Ser. No. 811,123 filed Dec. 19, 1985, hereby incorporated by reference. A prior art method for treatment of filamentary materials in a tube is found in U.S. Pat. No. 2,509,279.